Non-Planar Quantum Well Device Having Interfacial Layer and Method of Forming Same

ABSTRACT

Techniques are disclosed for forming a non-planar quantum well structure. In particular, the quantum well structure can be implemented with group IV or III-V semiconductor materials and includes a fin structure. In one example case, a non-planar quantum well device is provided, which includes a quantum well structure having a substrate (e.g. SiGe or GaAs buffer on silicon), a IV or III-V material barrier layer (e.g., SiGe or GaAs or AlGaAs), and a quantum well layer. A fin structure is formed in the quantum well structure, and an interfacial layer provided over the fin structure. A gate metal can be deposited across the fin structure. Drain/source regions can be formed at respective ends of the fin structure.

This application is a continuation of U.S. patent application Ser. No.14/804,019, filed Jul. 20, 2015 and entitled “Non-Planar Quantum WellDevice Having Interfacial Layer and Method of Forming Same”, which is acontinuation of U.S. patent application Ser. No. 14/060,557, filed Oct.22, 2013, now U.S. Pat. No. 9,087,887, issued Jul. 21, 2015 alsoentitled “Non-Planar Quantum Well Device Having Interfacial Layer andMethod of Forming Same”, which is a continuation of U.S. patentapplication Ser. No. 12/924,307, filed Sep. 24, 2010, now U.S. Pat. No.8,575,653, issued Nov. 5, 2013 also entitled “Non-Planar Quantum WellDevice Having Interfacial Layer and Method of Forming Same.” The contentof each of the above applications is hereby incorporated by reference.

BACKGROUND

Quantum well transistor devices formed in epitaxially grownsemiconductor heterostructures, typically in III-V orsilicon-germanium/germanium (SiGe/Ge) material systems, offerexceptionally high carrier mobility in the transistor channel. Inaddition, these devices provide exceptionally high drive currentperformance. However, non-planar quantum well transistors tend toexhibit charge spill-over and an electrically poor high-k dielectric andgermanium interface at least by virtue of the thin high-k material, inthis deleteriously affecting the performance of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a quantum well growth structure in accordance withone embodiment of the present invention.

FIG. 2 illustrates deposition and patterning of a hardmask on thequantum well growth structure of FIG. 1, in accordance with oneembodiment of the present invention.

FIG. 3 illustrates a shallow trench isolation (STI) etch to form agermanium fin structure on the quantum well growth structure of FIG. 2,in accordance with one embodiment of the present invention.

FIG. 4 illustrates deposition and planarization of dielectric materialaround the germanium fin structure of the quantum well growth structureof FIG. 3, in accordance with one embodiment of the present invention.

FIG. 5 illustrates etching to recess the STI dielectric material of thequantum well growth structure of FIG. 4, in accordance with oneembodiment of the present invention.

FIG. 6 illustrates gate electrode formation on the germanium finstructure of the quantum well growth structure of FIG. 5, in accordancewith one embodiment of the present invention.

FIG. 7 illustrates a perspective view of the device shown in FIG. 6,configured in accordance with an embodiment of the present invention.

FIG. 8 illustrates a method for forming a germanium fin based quantumwell structure, in accordance with one embodiment of the presentinvention.

FIG. 9 illustrates a system according to one embodiment.

DETAILED DESCRIPTION

Techniques are disclosed for forming a non-planar germanium quantum wellstructure exhibiting improved electrical performance. In particular, thequantum well structure can be implemented with group IV or III-Vsemiconductor materials and includes a germanium fin structure, so as toeffectively provide a hybrid structure. The techniques can be used, forexample, to improve short channel effects and gate length (Lg)scalability in a modulation/delta doped non-planar device.Electrostatics benefits of a fin-based device are achieved, whilesimultaneously retaining the high mobility benefits of amodulation/delta doped device.

As previously explained, quantum well transistor devices formed inepitaxially grown semiconductor heterostructures, for example in III-Vmaterial systems, offer very high carrier mobility in the transistorchannel. These conventional devices provide exceptionally high drivecurrent performance. Such quantum well systems may be fabricated withplanar architectures or with non-planar architectures.

Non-planar transistor architectures, such as FinFET structures (e.g.,double-gate, tri-gate and surround gate structures), can be used toimprove electrostatics and short channel effects, and hence enable Lgscalability. However, such non-planar architectures are generallyregarded as incompatible with high quality, high mobility, quantum welltransistors formed in epitaxially grown heterostructures. Thus, and inaccordance with an embodiment of the present invention, non-planar Gequantum well transistor device is provided including an interfaciallayer disposed between the Ge fin and the high-k layer. Optionally, anintermediate layer may be provided between the interfacial layer and thehigh-k layer in order to establish better electrical compatibility withthe high-k material, as will be explained in further detail below. Thedevice can be formed from semiconductor heterostructures, such as Ge,SiGe, Si, and/or gallium arsenide (GaAs), aluminum arsenide (AlAs). Anynumber of epitaxially grown heterostructures fabricated with group IV orIII-V materials can be configured with a germanium fin-based channel.The hetrerostructure can be patterned and etched into one or more narrowfins.

The process flow for fabricating the device can be implemented, forexample, in a similar fashion to that used in fabricating a conventionalsilicon based non-planar device, including shallow trench isolation(STI), gate stack, source/drain regions, and contact formation.

One advantage of a IV/III-V/Ge system configured in accordance with anembodiment of the present invention is that charge spillover in thenon-planar structure is greatly reduced, allowing charge confinement inthe Ge quantum well fin.

Thus, given a desired Ge quantum well structure, a fin structure (alongwith gate, source and drain regions, and contacts, etc) can be formed inaccordance with an embodiment of the present invention. So, inaccordance with one example embodiment, formation of a non-planar Gequantum well transistor device may generally include the provision of asilicon encapsulation layer or interfacial layer on the fin surfaces inorder to allow containment of the charge within the Ge quantum well fin.

FIG. 1 illustrates a cross-sectional side view of an example Ge quantumwell growth structure that can be used in producing a non-planargermanium quantum well device, in accordance with one embodiment of thepresent invention. The quantum well growth structure can be, forexample, a conventional SiGe/Ge or GaAs/Ge quantum well structure.Although no-capping layer is shown in FIG. 1, some embodiments mayinclude the provision of a capping layer on the structure, as would berecognized by one skilled in the art. Thus, as previously explained,however, note that a non-planar Ge quantum well transistor device formedin accordance with an embodiment of the present invention can beimplemented with any number quantum well growth structures, configuredwith various IV or III-V materials, optional doping layers, and bufferlayers, as will be apparent in light of this disclosure. The claimedinvention is not intended to be limited to any particular quantum wellgrowth configuration.

As can be seen in FIG. 1, the quantum well growth structure includes asubstrate, upon which nucleation and buffer layers are formed. Thestructure further includes a group IV or III-V material barrier layerupon which a spacer layer is formed, upon which a Ge quantum well layeris formed. Other embodiments may include fewer layers (e.g., fewerbuffer layers) or more layers (e.g., additional spacer and/or dopedlayers below quantum well layer) or different layers (e.g., formed withdifferent semiconductor materials, formulations, and/or dopants). Thelayers may be implemented with any suitable layer thicknesses and otherdesired layer parameters, using established semiconductor processes(e.g., metal organic chemical vapor deposition, molecular beam epitaxy,photolithography, or other such suitable processes), and may be graded(e.g., in linear or step fashion) to improve lattice constant matchbetween neighboring layers of otherwise lattice diverse materials. Ingeneral, the specific layers and dimensions of the structure will dependon factors such as the desired device performance, fab capability, andsemiconductor materials used.

The substrate may be implemented as typically done, and any number ofsuitable substrate types and materials can be used here (e.g., p-type,n-type, neutral-type, silicon, germanium, high or low resistivity,off-cut or not off-cut, bulk, silicon-on-insulator, etc). In one exampleembodiment, the substrate is a bulk Si substrate. In another exampleembodiment, the substrate is a bulk Ge substrate. Other embodiments mayuse a semiconductor on insulator configuration, such as silicon oninsulator (SOI) or germanium on insulator (GeOI) or SiGe on insulator(SiGeOI).

The nucleation and buffer layers are formed on the substrate, and alsomay be implemented as typically done. In one specific exampleembodiment, the nucleation and buffer layers are made of SiGe (e.g., 60%Ge) or GaAs and have an overall thickness of about 0.5 to 2.0 μm (e.g.,nucleation layer of about 25 nm to 50 nm thick and the buffer layer isabout 0.3 μm to 1.9 μm thick). As is known, the nucleation and bufferlayers can be used to fill the lowest substrate terraces with atomicbi-layers of, for example, III-V materials such as GaAs material. Thenucleation layer can by used to create an anti-phase domain-free virtualpolar substrate, and the buffer layer may be used to provide dislocationfiltering buffer that can provide compressive strain for a quantum wellstructure and/or control of the lattice mismatch between the substrateand the barrier layer. The buffer layers may also include a gradedbuffer, which can also be implemented as conventionally done. As isknown, by forming the graded buffer layer, dislocations may glide alongrelatively diagonal planes therewithin so as to effectively control thelattice mismatch between the substrate and the IV/III-V material barrierlayer (and/or any intervening layers). As will be apparent, such gradedlayers can be used in other locations the quantum well structure orstack. Note that other quantum well structures that can benefit from anembodiment of the present invention may be implemented without thenucleation and/or buffer layers. For example, embodiments having asubstrate and barrier layer that are implemented with materials havingsufficiently similar lattice constants may be implemented without agraded buffer.

The IV/III-V barrier layer is formed on the nucleation and buffer layerin this example embodiment, and can also be implemented asconventionally done. In one specific example embodiment, the barrierlayer is implemented with Si _(1-x)Ge_(x) (where x is in the range of 40to 80, such as 60), or GaAs, or Al_(1-x)Ga_(x)As (where x is in therange of 50 to 90, such as 70), and has a thickness in the range of 4 nmand 120 nm (e.g., 100 nm, +/−20 nm). Generally, the barrier layer isformed of a material having a higher band gap than that of the materialforming the overlying quantum well layer, and is of sufficient thicknessto provide a potential barrier to charge carriers in the transistorchannel. As will be appreciated, the actual make up and thickness of thebarrier layer will depend on factors such as the substrate and quantumwell layer materials and/or thicknesses. Numerous such barrier materialsand configurations can be used here, as will be appreciated in light ofthis disclosure.

If a doping layer is provided (not shown), the doping layer may beformed on (or within) the barrier layer in the example quantum wellgrowth structure, and can also be implemented as conventionally done. Ingeneral, the barrier layer can be doped by the doping layer to supplycarriers to the quantum well layer. For an n-type device utilizing aSiGe material barrier layer, the doping may be implemented, for example,using boron and/or tellurium impurities, and for a p-type device thedoping layer may be implemented, for example, using beryllium (Be)and/or carbon. The thickness of the doping layer will depend on factorssuch as the type of doping and the materials used. For instance, in oneexample embodiment the doping layer is a layer of boron delta dopedSi₄₀Ge₆₀ having a thickness between about 3 Å to 15 Å. In anotherembodiment, the doping layer is a layer of Be modulation doped GaAshaving a thickness between about 15 Å to 60 Å. The doping can beselected, for instance, based upon the sheet carrier concentration thatis useful in the channel of the Ge quantum well layer. As will beappreciated in light of this disclosure, an embodiment of the presentinvention may be implemented with quantum well structures having anytype of suitable doping layer or layers.

The spacer layer is formed on (or over) the buffer layer, and can alsobe implemented as conventionally done. In one specific exampleembodiment, the spacer layer is implemented with Si_(1-x)Ge_(x) (where xis in the range of 40 to 80, such as 60), or GaAs, or Al_(1-x)Ga_(x)As(where x is in the range of 50 to 90, such as 70), and has a thicknessin the range of 0.2 nm to 70 nm (e.g., 5 nm). In general, the spacerlayer can be configured to provide compressive strain to the quantumwell layer as it acts as a semiconductive channel. Note that otherquantum well structures that can benefit from an embodiment of thepresent invention may be implemented without the spacer layer.

The quantum well layer can also be implemented as conventionally done.In general, the quantum well layer is implemented with undopedgermanium, having an example thickness of about 20 Å to 500 Å. Numerousother quantum well layer configurations can be used here, as will beappreciated. In a more general sense, the quantum well layer has asmaller band gap than that of the IV/III-V barrier layer, is undoped,and is of a sufficient thickness to provide adequate channel conductancefor a given application such as a transistor for a memory cell or alogic circuit. The quantum well layer may be strained by the barrierlayer, an upper barrier layer, or both.

After formation of the device stack, which generally includes thesubstrate through the quantum well layer as previously described, acapping layer (not shown) may optionally be formed over the quantum welllayer. In one specific example embodiment, the capping layer isimplemented with SiGe or Si and has a thickness in the range of 2 to 10nm (e.g., 6 nm). As will be appreciated, other suitable capping layermaterials may be used to protect the underlying germanium quantum welllayer.

FIGS. 2 through 7 illustrate with cross-sectional and perspective viewsthe formation of a Ge fin-based quantum well structure configured inaccordance with an embodiment of the present invention. As will beappreciated, the fin-based structure can be formed on the device stackshown in FIG. 1, or any number of other quantum well growth structures.Note that intermediate processing, such as planarization (e.g., chemicalmechanical polishing, or CMP) and subsequent cleaning processes, may beincluded throughout the formation process, even though such processingmay not be expressly discussed.

FIG. 2 illustrates deposition and patterning of a hardmask on thequantum well growth structure of FIG. 1, in accordance with oneembodiment of the present invention. This patterning, which is forshallow trench isolation (STI) formation, can be carried out usingstandard photolithography, including deposition of hardmask material(e.g., such as silicon dioxide, silicon nitride, and/or other suitablehardmask materials), patterning the resist on a portion of the hardmaskthat will remain temporarily to protect the underlying fin structure (Gechannel in this case), etching to remove the unmasked (no resist)portions of the hardmask (e.g., using a dry etch, or other suitablehardmask removal process), and then stripping the patterned resist. Inthe example embodiment shown in FIG. 2, the resulting hardmask iscentral to the device stack and formed in one location, but in otherembodiments, the hardmask may be offset to one side of the stack and/orlocated in multiple places on the stack, depending on the particularactive device.

FIG. 3 illustrates a shallow trench isolation (STI) etch to form agermanium fin structure on the quantum well growth structure of FIG. 2,and FIG. 4 illustrates deposition and planarization of dielectricmaterial around the germanium fin structure, in accordance with oneembodiment of the present invention. The germanium fin is biaxiallycompressively strained a the outset by virtue of a lattice mismatchbetween the germanium and the IV or III/V material of the barrier layerand spacer layer. An etch of the material in the germanium layer resultsin a uniaxial strain in the resulting Ge fin This can also be carriedout using standard photolithography, including etching to removeportions of the stack that are unprotected by the hardmask (e.g., wet ordry etch), and deposition of a dielectric material (e.g., such as SiO₂,or other suitable dielectric materials). The depth of the STI etch mayvary, but in some example embodiments is in the range of 0 Å to 5000 Åbelow the bottom of the Ge quantum well layer. In this exampleembodiment, the etch depth is almost to the bottom of the materialbarrier layer. In general, the etch should be to a sufficient depth thatallows the quantum well channel to be electrically isolated (e.g., fromneighboring componentry or other potential interference sources), suchas, for example, down to the barrier layer or even down to the substratelayer. After formation of the STI and deposition of dielectric material,the deposited dielectric materials can be polished/planarized (e.g.,using CMP). Note the hardmask can be left on to protect the germaniumchannel.

FIG. 5 illustrates etching to recess the STI dielectric material of thequantum well growth structure of FIG. 4, in accordance with oneembodiment of the present invention. This can also be carried out usingstandard photolithography, including etching to remove the dielectricmaterial (e.g., using wet etch, but dry etch may be used as well). Thedepth of the recess etch may vary, but, for example, it may generally bebetween the bottom of the germanium quantum well layer (channel) andabove the spacer layer. As can be seen, in this example embodiment, therecess etch depth is to the bottom of the germanium quantum well layer(channel). Note the hardmask is still in place to protect the Ge finstructure (or channel).

FIG. 6 illustrates gate electrode formation on the germanium finstructure of the quantum well growth structure of FIG. 5, in accordancewith one embodiment of the present invention. The resulting structure,shown in perspective view in FIG. 7, is a effectively a Ge quantum wellstructure configured as a FinFET device (hence, non-planar). As isknown, a FinFET is a transistor built around a thin strip ofsemiconductor material (generally referred to as the fin). The FinFETdevice includes the standard field effect transistor (FET) nodes,including a gate, a gate dielectric (typically high-k), a source region,and a drain region (only one of source/drain regions is generally shownin FIG. 7). The conductive channel of the device resides on the outersides of the fin beneath the gate dielectric. Specifically, current runsalong both sidewalls of the fin (sides perpendicular to the substratesurface) as well as along the top of the fin (side parallel to thesubstrate surface). Because the conductive channel of suchconfigurations essentially resides along the three different outer,planar regions of the fin, such a FinFET design is sometimes referred toas a tri-gate FinFET. Other types of FinFET configurations are alsoavailable, such as so-called double-gate FinFETs, in which theconductive channel principally resides only along the two sidewalls ofthe fin (and not along the top of the fin). The height of the fin may bedetermined by device requirements, and may be limited only by etchingcapabilities.

As can be seen be in FIG. 6, according to an embodiment, the hardmaskmay be removed (e.g., wet or dry etch) and an interfacial layer may beprovided over the Ge channel. This interfacial layer can be, forexample, a layer of silicon, which may be epitaxially provided onto allof the surfaces of the Ge fin. As seen in FIG. 6, the interfacial layercovers all active surfaces of the fin, that is, the exposed 100 (topsurface of fin) and 110 (side surfaces of fin) surfaces as shown. In thecase of a double-gate device, the interfacial layer may cover only the110 or side surfaces of the fin, the top 100 surface of the fin beingprovided with an insulation layer such as silicon nitride. Theinterfacial layer may include one or more layers, such as one or moremonolayers of silicon. Preferably, the interfacial layer is as thin aspossible. For example, the interfacial layer may include a monolayer ofsilicon epitaxially provided onto the fin. The thinness of theinterfacial layer is advantageous to prevent any empty states, chargecenters or defects being present within the interfacial layer, in thisway preventing the migration of charges into the interfacial layer fromthe fin. The thicker the interfacial layer, the more of a chance that amaterial of the interfacial layer, such as silicon, would create defectsat its interface with the germanium material of the fin by virtue of thelattice mismatch between the interfacial layer material and the finmaterial. However, an interfacial layer that is thicker than a monolayerof the interfacial layer material is also within the purview ofembodiments, as long as it effectively prevents the migration of chargefrom the fin material toward the high-k material. Materials that wouldbe suitable for the interfacial layer would have higher bandgaps thanthe bandgap of the fin material. In order to ensure a defect-freeinterfacial compatibility between the interfacial layer and the materialof the fin, preferably, the interfacial layer is provided in such as away as to present atom-to-atom bonding with the material of the fin.Thus, a preferred way of provided the interfacial layer is by way ofepitaxy. The thickness of the interfacial layer can be, for example,between about 3 Å to about 9 Å.

Referring still to FIG. 6, optionally, an intermediate layer may beplaced between the interfacial layer and the high-k layer. Anintermediate layer may offer an electrical advantage where the materialof the high-k layer has a tendency to present an interfacialincompatibility (e.g. the presence of dangling bonds) with the materialof the interfacial layer. By way of example, where the high-k layercomprises hafnium oxide, and where the interfacial layer comprisessilicon, an interface between the two layers may tend to presentdangling bonds or defects that may allow the migration of chargetherein. In such cases, it may be desirable to provide an intermediatelayer between the high-k layer and the interfacial layer in order tomitigate the interfacial compatibility mentioned above, and to providesubstantially electrically inert interfaces with the high-k layer on theone hand and with the interfacial layer on the other hand. A suitablematerial for the intermediate layer may include silicon dioxide. Ingeneral, the intermediate layer may include any dielectric material,such as for example a high-k or a low-k dielectric that provides anelectrically compatible interface (i.e., an interface with no danglingbonds, defects or charge centers) with the material of the high-k layer.The intermediate layer may, for example, include alumina, zirconia orhafnium silicate. Where the interfacial layer includes silicon, anintermediate layer including silicon dioxide may be provided byoxidizing a surface of the silicon interfacial layer in a conventionalmanner, any other suitable way of providing an intermediate layer beinghowever within the purview of embodiments. For example, the intermediatelayer may be deposited according to any well known method of providing adielectric layer, such as for example by using CVD, PVD or ALD. Thethickness of the intermediate layer may be, for example, between about 5Å to about 10 Å. To the extent that the material of the intermediatelayer may include a dielectric material, it would serve as part of thegate dielectric including the high-k layer. As a result, a thickness ofthe high-k layer and of the intermediate layer may be determined toachieve an optimal result in terms of dielectric effectiveness andinterfacial compatibility as would be recognized by one skilled in theart.

Referring still to FIG. 6, the high-k gate dielectric deposited on thetop barrier can be, for instance, a film having a thickness in the rangeof 10 Å to 50 Å (e.g., 20 Å), and can be implemented, for instance, withhafnium oxide, alumina, tantalum pentaoxide, zirconium oxide, lanthanumaluminate, gadolinium scandate, hafnium silicon oxide, lanthanum oxide,lanthanum aluminum oxide, zirconium silicon oxide, tantalum oxide,titanium oxide, barium strontium titanium oxide, barium titanium oxide,strontium titanium oxide, yttrium oxide, aluminum oxide, lead scandiumtantalum oxide, lead zinc niobate, or other such materials having adielectric constant greater than that of, for instance, silicon dioxide.The high-k gate dielectric may be provided according to any one of wellknown methods, such as, for example, using PVD, CVD or ALD. In general,there need not exist an atom-to-atom bond between the high-k layer andan intermediate layer if the intermediate layer is provided, as long asthe provision of the intermediate layer substantially eliminatesdangling bonds in the interfacial region between the fin material andthe high-k material.

Referring still to FIG. 6, the gate metal deposited over the high-k gatedielectric can be, for example, nickel, gold, platinum, aluminum,titanium, palladium, titanium nickel or other suitable gate metal oralloy. Source and drain regions can be formed as conventionally done fora FinFET structure, and may be configured with the same metal as thegate or another suitable contact metal. As will be appreciated in lightof this disclosure, the top barrier, high-k gate dielectric, gate metal,and source/drain regions can be implemented using standard FinFETprocessing.

FIG. 8 illustrates a method for forming a germanium fin based quantumwell structure, in accordance with one embodiment of the presentinvention. The quantum well structure can be configured as desired, andgenerally includes a stack that includes a substrate, a IV/III-V barrierlayer, and a quantum well layer.

The method includes patterning 803 a hardmask for shallow trenchisolation (STI) patterning. The patterning may include, for instance,deposition of hardmask material, patterning resist on a portion of thehardmask that will remain temporarily to protect the underlying finstructure of the device during STI etching, etching to remove theunmasked (no resist) portions of the hardmask (e.g., using a dry etch,or other suitable hardmask removal process), and then stripping thepatterned resist, to provide a patterned STI hardmask.

The method continues with etching 805 a STI into Ge quantum wellstructure, thereby forming a fin structure. In one example case, and aspreviously explained, the trench formation can be carried out using aone or more dry and/or wet etches. The method continues with depositing807 dielectric material into the STI, and planarizing that dielectricmaterial. The method continues with etching 809 to recess the STImaterial (e.g., down to the bottom of the Ge quantum well layer, andbefore the doping layer). The etch can be implemented, for instance,with a wet etch.

The method continues with providing 811 an interfacial layer andoptional intermediate layer over the fin structure. Thereafter, themethod continues at 811 by the provision of a high-k layer. The high-kgate dielectric can be, for instance, a film having a suitable thicknessto sufficiently isolate the metal gate and a dielectric constant greaterthan that of, for instance, silicon dioxide. Other suitable gatedielectrics can be used (e.g., non-high-k dielectrics) here as well, andin some embodiments where the top barrier provides sufficient isolationon its own, no gate dielectric may be needed. The method continues withdepositing 812 gate metal over the top barrier and across the isolatedGe fin structure forming the device channel, and forming 815 drain andsource regions at respective ends of the fin structure (channel). Thegate metal and source/drain regions can be implemented using standardprocessing (deposition, masking, etching, planarizing, etc).

Thus, a non-planar quantum well structure configured with an interfaciallayer sandwiched between the fin and the high-k layer may be provided.The structure can be used, for example, as a FinFET device (e.g.,double-gate or tri-gate FinFET) suitable for use in numerousapplications (e.g., processors, memory, etc).

Numerous embodiments and configurations will be apparent in light ofthis disclosure. For instance, one example embodiment of the presentinvention provides a method for forming a non-planar quantum wellstructure. The method includes receiving a quantum well structure havinga substrate, a IV or III-V material barrier layer, and an undopedgermanium quantum well layer. The method further includes selectivelyetching the quantum well structure to form a germanium fin structure,depositing a interfacial layer and an optional intermediate layer overthe fin structure, and depositing gate metal across the fin structure.In one particular case, selectively etching the quantum well structureincludes patterning a hardmask on the quantum well structure for shallowtrench isolation (STI) patterning, etching an STI into the quantum wellstructure, depositing dielectric material into the STI, and planarizingthe dielectric material. In one such case, the dielectric material inthe STI is recessed down to a bottom of the germanium quantum welllayer. The method may include forming drain and source regions atrespective ends of the fin structure. In another particular case, afterdepositing a interfacial layer over the fin structure and prior todepositing gate metal across the fin structure, the method furtherincludes depositing a high-k gate dielectric layer over the interfaciallayer. The quantum well structure can be, for example, an epitaxiallygrown heterostructure. A doping layer if provided may include, forinstance, delta doping which modulation dopes an undoped germaniumquantum well layer. In another particular case, an undoped germaniumquantum well layer can be epitaxially grown after the doping layer. Inone embodiment, the quantum well fin may be doped. In yet anotherembodiment, to further enhance the compressive strain within the fin,recessed source and drain regions may be provided and filled with aIII/V or a SiGe material.

Another example embodiment of the present invention provides anon-planar quantum well device. The device includes a quantum wellstructure having a substrate, a IV or III-V material barrier layer, anda germanium quantum well layer. The device further includes a germaniumfin structure formed in the quantum well structure, a interfacial layerprovided over the fin structure, an optional intermediate layer providedover the interfacial layer, and gate metal deposited across the finstructure. The device may include, for example, recessed dielectricmaterial in shallow trench isolation (STI) proximate the fin structure.In one such case, the dielectric material in the STI is recessed down toa bottom of the germanium quantum well layer. The device may includedrain and source regions formed at respective ends of the fin structure.The device may include a high-k gate dielectric deposited between theinterfacial layer and gate metal. In one example case, the non-planarquantum well structure comprises a FinFET device. In another examplecase, the IV or III-V material barrier layer is implemented with silicongermanium or gallium arsenide or aluminum gallium arsenide, and thesubstrate comprises a silicon germanium or gallium arsenide buffer onsilicon. In another example case, the quantum well structure is anepitaxially grown heterostructure. In another example case, a dopinglayer if provided may include delta doping, which modulation dopes anundoped germanium quantum well layer. In another example case, anundoped germanium quantum well layer is expitaxially grown after thedoping layer (on or within the barrier layer).

It will be appreciated that embodiments encompass the provision of aplurality of fin structures on a substrate, and that processes forforming a plurality of nMOS transistor structures or pMOS transistorstructures may be performed on multiple fin structures in parallel.Thus, a single fin structure is shown here for the sake of simplicity.In addition, embodiments are not limited to the use of a germanium fin,but include within their scope the use of a fin made of any othersuitable material.

FIG. 9 shows a computer system according to an embodiment. System 900includes a processor 910, a memory device 920, a memory controller 930,a graphics controller 940, an input and output (I/O) controller 950, adisplay 952, a keyboard 954, a pointing device 956, and a peripheraldevice 958, all of which may be communicatively coupled to each otherthrough a bus 960, in some embodiments. Processor 910 may be a generalpurpose processor or an application specific integrated circuit (ASIC).I/0 controller 950 may include a communication module for wired orwireless communication. Memory device 920 may be a dynamic random accessmemory (DRAM) device, a static random access memory (SRAM) device, aflash memory device, or a combination of these memory devices. Thus, insome embodiments, memory device 920 in system 900 does not have toinclude a DRAM device.

One or more of the components shown in system 900 may include one ormore non-planar devices of the various embodiments included herein. Forexample, processor 910, or memory device 920, or at least a portion ofI/0 controller 950, or a combination of these components may include inan integrated circuit package that includes at least one embodiment ofthe structures herein.

These elements perform their conventional functions well known in theart. In particular, memory device 920 may be used in some cases toprovide long-term storage for the executable instructions for a methodfor forming structures in accordance with some embodiments, and in otherembodiments may be used to store on a shorter term basis the executableinstructions of a method for forming structures in accordance withembodiments during execution by processor 910. In addition, theinstructions may be stored, or otherwise associated with, machineaccessible mediums communicatively coupled with the system, such ascompact disk read only memories (CD-ROMs), digital versatile disks(DVDs), and floppy disks, carrier waves, and/or other propagatedsignals, for example. In one embodiment, memory device 920 may supplythe processor 910 with the executable instructions for execution.

System 900 may include computers (e.g., desktops, laptops, hand-helds,servers, Web appliances, routers, etc.), wireless communication devices(e.g., cellular phones, cordless phones, pagers, personal digitalassistants, etc.), computer-related peripherals (e.g., printers,scanners, monitors, etc.), entertainment devices (e.g., televisions,radios, stereos, tape and compact disc players, video cassetterecorders, camcorders, digital cameras, MP3 (Motion Picture ExpertsGroup, Audio Layer 3) players, video games, watches, etc.), and thelike.

The foregoing description of example embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseforms disclosed. Many modifications and variations are possible in lightof this disclosure. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

What is claimed is:
 1. A method of forming a non-planar quantum wellstructure, comprising: providing a quantum well structure including asubstrate and a quantum well layer that includes a channel region;selectively etching the quantum well structure to form a fin structurethat is: (a) formed in the quantum well structure, and (b) includes thequantum well layer; providing a dielectric layer over the fin structure;and providing gate metal over the dielectric layer.
 2. The method ofclaim 1, wherein the quantum well layer includes germanium.
 3. Themethod of claim 1 comprising: providing an interfacial layer over thefin structure, a material of the interfacial layer having a higherbandgap than a bandgap of a material of the fin structure; and providingan intermediate layer over the interfacial layer prior to providing thedielectric layer.
 4. The method of claim 3, wherein the interfaciallayer comprises epitaxially grown silicon.
 5. The method of claim 3,wherein the intermediate layer comprises a dielectric material differentfrom a material of the dielectric layer.
 6. A non-planar quantum welldevice comprising: a quantum well structure including a substrate and aquantum well layer that includes a channel region; a fin structure that:(a) is included in the quantum well structure and, (b) includes thequantum well layer; a dielectric layer over the fin structure; and agate material over the dielectric layer.
 7. The device of claim 6,wherein the quantum well layer includes germanium.
 8. The device ofclaim 6 comprising an intermediate layer and an interfacial layer,wherein the intermediate layer is between the interfacial layer and thedielectric layer.
 9. The device of claim 6 comprising an interfaciallayer that covers a 100 surface and a 110 surface of the fin structure.10. The device of claim 6 comprising an interfacial layer, over the finstructure, which comprises silicon.
 11. The device of claim 10, whereinthe silicon is epitaxial.
 12. The device of claim 6, comprising aninterfacial layer, over the fin structure, which comprises a singlemonolayer of atoms.
 13. The device of claim 8, wherein the intermediatelayer comprises a dielectric material different from a material of thedielectric layer.
 14. The device of claim 13, wherein the intermediatelayer comprises at least one of silicon dioxide, alumina, zirconia andhafnium silicate.
 15. The device of claim 8, wherein the intermediatelayer includes a material obtained from an oxidization of a surface ofthe interfacial layer.
 16. The device of claim 6 comprising drain andsource regions at respective ends of the fin structure.
 17. The deviceof claim 6, wherein the quantum well structure further includes a dopinglayer.
 18. The device of claim 6, wherein the quantum well layer isepitaxial.
 19. A system comprising: a processor including: a quantumwell structure including a substrate and a quantum well layer thatincludes a channel region; a fin structure that (a) is included in thequantum well structure and, (b) includes the quantum well layer; adielectric layer over the fin structure; and a gate material over thedielectric layer; and a memory coupled to the processor.
 20. The systemof claim 19 comprising an interfacial layer and an intermediate layer;wherein (a) the interfacial layer is over the fin structure; (b) theinterfacial layer comprises epitaxial silicon, and (c) the quantum wellstructure includes the intermediate layer, included between theinterfacial layer and the dielectric layer, which comprises silicondioxide.